Design a 400KHz, 12V to 300V inverter

[TomAzawill]

Hi there. I need your help to design a 12v DC to 300v AC inverter with LMC555. The square wave frequency need to be 400KHz. Do anyone have a schematic? Thanks a lot.

 

[marce]

Do you understand the implications of working with high voltages? Creapage and clearance...

 

[schmitt trigger]

What power level do you require?
Do you have expertise in designing PC boards for high frequency design? Please don't tell me that you are planning to build it on a stripboard.

 

[d123]

Hi Tom,

Wow! There's this new thing called doing an Internet search, not sure how it works, but this came up:

12vDC to 300vAC using 555

These are two circuits you could look at, the second doesn't use the 555, instead the CD4047, it's the same idea, they look interchangeable. Someone with a keener eye may be able to say if both are "good" circuits to use as a base.

12VDC to 220VAC Inverter with 555 Timer

Simple 100W inverter circuit

I really have to ask: Are you an engineer/electrician, or are you a person who has little experience and wants to make this for some reason (and do you have at least a suitable DMM to measure voltages with)?

KlausST needs to show up and write in red text: Dangerous voltages. Be careful. etc. I mean it seriously if you have little experience of circuits - a pound of preparation beats a horrible accident or just burnt circuits, so really do read up on posts #2 and #3's suggestions first, please. My apologies if you know exactly what you are doing.

 

[TomAzawill]

What power level do you require?
Do you have expertise in designing PC boards for high frequency design? Please don't tell me that you are planning to build it on a stripboard.

Thank you. It's easy to make 555 generate 400KHz square wave at 12V. My problem is to boost this square wave to 300V. I will try this on sripboard first.

 

[TomAzawill]

Hi Tom,

Wow! There's this new thing called doing an Internet search, not sure how it works, but this came up:

12vDC to 300vAC using 555

These are two circuits you could look at, the second doesn't use the 555, instead the CD4047, it's the same idea, they look interchangeable. Someone with a keener eye may be able to say if both are "good" circuits to use as a base.

12VDC to 220VAC Inverter with 555 Timer

Simple 100W inverter circuit

I really have to ask: Are you an engineer/electrician, or are you a person who has little experience and wants to make this for some reason (and do you have at least a suitable DMM to measure voltages with)?

KlausST needs to show up and write in red text: Dangerous voltages. Be careful. etc. I mean it seriously if you have little experience of circuits - a pound of preparation beats a horrible accident or just burnt circuits, so really do read up on posts #2 and #3's suggestions first, please. My apologies if you know exactly what you are doing.

Thank you. I also found searched these schmetics online. The problem is they all working at 50Hz, a very low frequency but I need 400KHz. I adjusted the resistor/capacitor of 555 and tried to simulated these circuits in Multisim at a high frequency but failed because of Multisim simulation error. So my question is can I just change the 555 output freq on a general 12vDC to 300vAC inverter?

 

[d123]

Hi,

One thing I would recommend is - if you have the components for the 555 part of the circuit and a breadboard (easier than deadbug, but with drawbacks) - measure the output voltage of the 555, ideally with a oscilloscope, with your expected load connected to check that the 555 will output anything close to 12V squarewave at 400kHz. Don't want to be doom and gloom and/or wrong in your case, but some of my simulation errors are in fact not errors but circuits that don't work and the simulator tells me that way.

I suspect - and may be wrong - that a 555 driving a transformer that goes from 12VDC to 300VAC may be defying the laws of nature somewhat. Some-one else will know if that's so.

...breadboards are apparently terrible for high frequency circuits, and stripboard (that's perf. board, right?) with a load of wires and the rest may not be any better. It's a mantra to learn: solid ground plane.

Rather that use the 555 to generate 12V/400kHz, even the CD4060 and a suitable crystal oscillator, followed by a BJT driving a mosfet for the transformer might be a "better" option, but pay me no mind.

 

[marce]

Thank you. I also found searched these schmetics online. The problem is they all working at 50Hz, a very low frequency but I need 400KHz. I adjusted the resistor/capacitor of 555 and tried to simulated these circuits in Multisim at a high frequency but failed because of Multisim simulation error. So my question is can I just change the 555 output freq on a general 12vDC to 300vAC inverter?

Do you understand creepage and clearance distances and all the other stuff that you need to be aware of when working with high voltage. Do you know what sort of transformer you will need and the wire you will have to use on it. Skin effect is going to come into play... how do you avoid skin losses... Filtering.

 

[Relayer]

Hello TomAzawill,
Why is it so vital that you need a 400kHz output and not a mains frequency of 50 or 60Hz depending upon the country you live in?
Regards,
Relayer

 

[TomAzawill]

It's for a medical instrument. Requires high voltage, high frequency but low output current. I studied analog circuit a few years ago but never did anything of power inverter. Thank you for asking. It would be great if you can give me more suggestion.